60 posts from March 2012

March 31, 2012

I know, what is a MCS? It stands for Mesoscale Convective System. They have been called other things such as MCC, Mesoscale Convective Complex and MCV...Mesoscale Convective Vortex. Either way, the idea is that this is a complex of thunderstorms that are very common in NW wind flows. They sometimes look like a mini low pressure with a warm front/cold front look to them. They can be dangerous however when it comes to high winds as it bows out. Tornado threat is low, but most common on the bottom/south edge of them. We typically see these in June/July.

Tomorrow is a good setup for one to form to our north. HPC shows the showers/storms forming in N IL.

They like to follow a track..like a locomotive. That would be the warm front that will pass through tomorrow. Where that front sets up is key on how close this complex will reach us.

As the MCS tracks south east, it will hunt for high dewpoint areas...so it is likely it will take a right turn at some point like I have drawn below.

As of right now, this impact looks to stay just east of our viewing area. But I only am posting this as there is a chance the warm front could be closer than forecast---and if so---the MCS may impact our eastern counties Sunday afternoon.

SPC has a small outlook out for this now: only 5% which is below SLIGHT RISK level.

Next SPC update is at 130pm.

UPDATE: SPC just upgraded SE IN/OH and far NE KY into a SLIGHT RISK for severe storms with the latest upset.

I would plan for a nice/warm day for now...with at least some cirrus clouds steaming over in the afternoon from this. We will watch the trends carefully to see how it evolves. Still have 24 hours.

Most of the day will be warm with a mixture of clouds and sunshine, but we have a chance of storms after 4pm. Some of those storms could be strong to severe with large hail as the main threat, damaging winds as the second threat. There is a very minimal threat of a tornado.

March 29, 2012

Beautiful day out there today! This is what spring is supposed to be like !

Don't forget we will be out at the Southeast YMCA this evening from 5-8pm for the Weather Tour!

Kevin, myself, Lauren and Christie will be there. Andy is going to hold back at the station for the newscasts.

Looking ahead, still looking at a chance for some strong storms Friday afternoon/night.

SPC still has *some of* us outlooked Friday. They did shift it a bit north.

Here is the % risk for severe:

Pretty easy setup to gauge as it will be a low pressure moving from MO to OH during the day Friday. The cold front attached to it will lag like a tail. So that means the storms will fire north...but will take a bit longer to move through our area to the south. This likely will be a slanted squall-line of storms from OH southwest toward Evansville by late afternoon/evening. The closer to the low pressure you are---the higher the risk for severe storms. So those of you across IN have a higher risk than our southern counties in KY.

The wind fields are decent, but nothing impressive.

NAM: GFS:

CAPES are certainly there...near 1500...so there is will be instability at play.

EHI's are slightly elevated, so I would not rule out a tornado warning or two that may get issued in the Ohio Valley---but this isn't a great setup for tornadoes (shew) as the winds at the surface and aloft are mostly SSW. No drastic change in direction between the two levels--but enough for a brief rotating storm.

The weekend looks to start off cool--and warm FAST. It is interesting to see how the NAM is 10 degrees cooler for Saturday than the GFS. NAM says 64...GFS says 74. We plan to split the difference right now with 70 more likely.

GFS really has warmed us up for Sunday...perhaps near 85? That is certainly possible given how quickly our southerly flow kicks in. In general, Sunday will be warmer than Saturday for those of you planning activities outside :)

The 'big storm' that was slated for Monday ...looks like a mess on the models now. GFS/EURO both had a strong low pressure near the Great Lakes with a negatively-tilted trough moving toward us. Well, EURO is weaker with the low...with a fast moving cold front. GFS decided to cut the low off from the main flow and has it slowly moving over us most of next week with a heavy rain threat.

In other words, the threat for a signficant outbreak of severe storms is lower today than it looked yesterday---but the models are struggling on how to handle this storm so I HIGHLY urge caution with the forecast for early-mid next week. Keep checking back in.

Here is the GFS for early next week.

Notice how the low gets cutoff from the main jet to the north.

IF the GFS verifies, heavy rain would be an issue. It is indicated the risk of 2-4" of rain.

SPC (before the GFS updated) did place a risk for severe storms to our south/west. Obviously, more adjustments on that will be needed as the models figure this thing out.

EURO as I mentioned also changed its tune.

Here is how it sees the map by Tuesday/Wednesday. Keeps the low with the main jet..but fast with it.

NOTE: new EURO is due out after this blog post...I will let you know if any drastic changes.

It is worth mentioning the Canadian model likes the GFS idea. Cutoff low. But MUCH slower with it . It does not push the low east of us until next Friday!

So what about cold/snow? Well, in order to turn colder...you need a strong area of low pressure to push it south. Now that we are talking about a cutoff low possibility---it will be a huge struggle to get colder air south.

GFS still hints at a taste perhaps by the 9th...but no snow showing up yet.

SUMMARY: Forecast looks pretty easy over the next few days...but next week looks complicated. I do think a signifcant storm system of some type is going to affect us...but we need to nail down if we are facing a severe storm setup or a heavy rain setup. Temps will likely cool quite a bit under that cutoff low---so next week may start off warm---but it will be a cool week overall the way it is looking.

QUESTION(S):How many times a week do you read the blog?What do you want to see more of with the posts?Do you like more graphics than words..or other way around?Do the times of day they get updated work out well for you?

We had severe storms yesterday, and we have another risk of severe storms tomorrow. One more reason to enjoy today, since we get to take a breather from the storms. Check out this picture of the hail yesterday near the Franklin/Scott County line... courtesy Don Dziubakowski:

Tomorrow we are under a slight risk of severe storms... mainly in the afternoon and evening. Main threats are large hail and wind damage.

The one great thing that the storms did yesterday was... they lowered the pollen in the air! Yay! It certainly makes for a less snotty Thursday at least. Here's the pollen forecast for the rest of the week from The Weather Channel:

March 28, 2012

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This will be a line of storms that will sag north to south this afternoon/evening. Many areas will be in the clear by 6pm so the watch likely will get cleared early.

Beyond tonight's event, we have (2) more severe weather possibilities we need to watch out for.

Friday and Monday.

FRIDAY:There will be an area of low pressure that will track north of us from IL into OH. There will be a pockets of decent winds aloft near that low that will help support severe thunderstorms in the afternoon/early evening.

SPC does have Louisville/northward included in a SLIGHT RISK for severe storms for this event.

Capes (instability) certainly looks to be there.

NAM- around 1500 GFS around 1000 with 1500 north/west

Winds aloft are pretty strong with the strongest closer to the low itself.

EHI index isn't off the chart, but high enough that a few isolated tornadoes cannot be ruled out in the region...especially north of Louisville into OH.

We will watch the model trends as we get closer.

MONDAY:This one is going to be tough to nail down---so keep in mind there will likely be changes on this. Especially with timing.

GFS/EURO both pretty robust with a strong low pressure (987mb) moving into the Great Lakes Sun-Tue. The low looks to become negatively tilted...or leans in a NW to SE fashion. This usually means a higher threat for severe thunderstorms in our area.

GFS shows the front moving in Monday PM with thunderstorms.

CAPES do surge quite a bit into the Ohio Valley.

The problems remains with timing. CMC/GEM models delay this low pressure until THURSDAY!

Right now, I think the GFS/EURO movement of Monday makes more sense...but we may have to push timing into Tuesday if the low becomes cutoff quicker than expected.

SPC does not have an outlook out for this event...but did issue the following statement:

WHILE THE PASSAGE OF THIS SYSTEM ACROSS THE CENTRAL -- AND EVENTUALLY THE ERN/NERN U.S. -- WOULD LIKELY BE ACCOMPANIED BYFAIRLY SUBSTANTIAL SEVERE POTENTIAL...THE DIFFERENCES IN TIMING AND EVOLUTION OF THIS SYSTEM AS DEPICTED IN THESE TWO MODELS CAST CONSIDERABLE DOUBT AS TO EVEN ROUGH APPROXIMATIONS OF TIMING AND LOCATION. THE ECMWF APPEARS SUBSTANTIALLY MORE ROBUST WITH RESPECT TO SEVERE POTENTIAL -- PARTICULARLY BEYOND DAY 4...WITH ITS MUCH SLOWER/NEGATIVELY-TILTED PROGRESSION OF THE TROUGH INTO THE PLAINS

Beyond this storm, there is a risk anyway for colder weather to move in around Wed or Thur next week.

850 temps do crashed behind the low...which normally would mean snow would fall. However, surface temps would be around 40. Granted, it CAN snow at 40...it would obviously melt.

GFS has 850mb temps at about -3C next Wed/Thu. For this time of year, I would like to see values more around -6 to -8 to actually put snow in the forecast. Right now, it just looks too marginal. GFS/EURO have bounced back and forth on this idea of a cold snap for over a week now. We will tackle this more next week.

April looks to be an interesting month with cold air really building in southern Canada. This creates a tight temperature gradient across the eastern US. This will mean strong areas of low pressure.

Most of the day will be dry with partly sunny skies, however, you have a 40% chance to see a shower or storm. The window of opportunity for these storms will be between noon and 6pm. We expect dry weather and clearing skies close to sunset. The storms that develop this afternoon have the potential to become severe with high winds and large hail.

QPF shows light rain totals, and most of the rain expected to be south of the Ohio River.

Join us for the WAVE 3 Weather Tour tomorrow (Thursday) at the Southeast YMCA in Louisville! Kevin Harned, Brian Goode, Lauren Jones and I will be there from 5pm-8pm. Come out and say howdy. Everyone is invited, and we'd love to see you.

March 27, 2012

Good afternoon, friends. Did you notice anything different this morning? How about the temperatures! Brr...it was a shock to the system for me as I've become accustomed to the record breaking heat we had last week. :) Check out these morning lows...areas to our North and East as expected nearly hit freezing. Outlying locations picked up some patchy frost. This mornings chill will be short lived as 80 degree heat makes a return.

TODAY/TONIGHT

Sunshine will rule the roost today. Temperatures will have a long way to climb to get back into the 70s after starting in the 30s and 40s...but it shouldn't be an impossible climb. Areas to our South and West should see the warmest temperatures today as a warm front moves closer. Upper 70s is likely in those locations while I expect the metro and surrounding counties to top out in the low 70s and cooler to the North and East. As we head into the evening hours clouds will build in from the West. These clouds are in advance of our next rain maker that will arrive tomorrow. Temperatures won't cool as much tonight as last night because clouds will act as a blanket and keep temps steady in the mid to upper 50s away from the city and low to mid 60s in and around the metro area.

TOMORROW

An area of low pressure will track through the Midwest and arrive in our area throughout the day tomorrow. Prior to it’s arrival a warm front will march Northward…a cold front Eastward…and we’ll be in a prime warming location by tomorrow afternoon. Temps will warm to near 80 tomorrow and with the daytime heating a few storms could fire in the afternoon. Any storm that develops will have the potential to become strong or severe. We feel the best location for this would be in Southern KY with damaging winds and hail being our main concern. After the cold front passes by tomorrow evening colder air will pour in Thursday with highs in the upper 60s and low 70s. Sunshine will continue throughout the day on Thursday.

NEW ORLEANS FORECAST

Scattered showers and storms are possible through the weekend in NOLA. Temperatures Friday – Monday will remain near 80. We don’t expect a wash out but with the afternoon heating pop up showers and storms are possible. Good Luck to the Cards and UK! We’ll continue to update the New Orleans forecast the next several days. Have a wonderful afternoon.